Author(s): G. Scharler
Linked Author(s):
Keywords: Keywords: spillway; Stilling basin; Pier; Ramp; Ogee; Hydraulic model studies; Cavitation; Aeration; Scour
Abstract: Birecik Dam and Hydroelectric Power Plant, located on the Euphrates river 80 km downstream of Atatuerk Dam, is planned to pass a flood of more than 17, 000 m 3 /s over a head of 40 m. For final design in 1994, it was necessary to revise the design of the stilling basin to allow for the planned excavation of the downstream river bed, needed to increase the head by some 3. 2 m at the maximum turbined discharge of1900 m3/s. Following preliminary design studies, Verbundplan undertook scale model spillway studies at the Ankara Technical University. For a hydraulic jump of 25 m depth, the stilling basin invert would have been 16 m below the planned river bed. Given the size of the basin, 30. 000 m 2 in area, the new tests showed it would not be advisable to try to minimize the length and depth of the basin to save rock excavation, in addition the light-weight limestone foundation rock called for deep anchoring to counteract uplift forces on the stilling basin. The tests showed that the basin floor had to be lowered by one meter to ensure against jump sweepout. Furthermore, the tests confirmed that the length could safely be reduced to 80 percent of that of a USBR Type 1 stilling basin, and this compensated for the additional excavation volume needed to reach the required depth. The tests also showed the design of the channel transition and the planned river bed level to be correct and gave acceptable scour patterns on the riverbed downstream of the stilling basin.
Year: 1999